This invention relates to a driving device for a hardness measuring instrument of the type including a fixed structure having a base member on which a piece to be measured is firmly resting, and a movable assembly comprising the measuring instrument proper, which is operated by a motor means during a measure cycle in such a manner as to be initially brought nearer the piece to be controlled and subsequently subjected to a measuring load.
In such hardness measuring instruments it is preferred that the instrument is moved rapidly but without any particular force toward a piece to be measured, and then pressed slowly but with considerable force against the piece, in order that reliable measurements can be obtained.
Once the required load is attained, the instrument is stopped and left in pressed condition under said load for a desired time, depending on the nature of the material of which the piece is made.
These hardness measuring instruments are usually operated by hydraulic means and are very much complicated in structure and, thus, subject to disadvantages.
For example, with these instruments, the above described type of handling is difficult to achieve and, as the stopping of the instrument at no time is instantaneous, due to the inertia of the driving means, a mismeasurement can be the result.